I installed the latest CentOS (release 5.9)
At the present time the latest CentOS release is 6.4.
As to the delay... As a test set the DNS Servers in the Guest OS to your know DNS Servers and see if that makes any difference. Or try using Google DNS or Open DNS Servers. Google Public DNS Servers are, 8.8.8.8 and 8.8.4.4. Open DNS Servers are, 208.67.222.222 and 208.67.220.220. Either will give a good test to see whether or not the lag is because of VMware's NAT having issues translating or using the IP Addresses directly with the Guest's NIC so it goes directly to the know DNS Servers.
If by explisitly setting the DNS Servers the lag is gone you can choose to leave it set or go back to the lag with just VMware NAT resolving everything.